Geometry of numbers and degree bounds for rational invariants

Fuente: arXiv
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Main Authors: Blum-Smith, Ben, Crane, Sylvan, Guzman, Karla, Menenses, Alexis, Song-Hurewitz, Maxine
Format: Preprint
Published: 2026
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author Blum-Smith, Ben
Crane, Sylvan
Guzman, Karla
Menenses, Alexis
Song-Hurewitz, Maxine
author_facet Blum-Smith, Ben
Crane, Sylvan
Guzman, Karla
Menenses, Alexis
Song-Hurewitz, Maxine
contents We investigate degree bounds for fields of rational invariants of representations of finite groups. We prove many cases of a bound for $\mathbb{Z}/p\mathbb{Z}$ conjectured by Blum-Smith, Garcia, Hidalgo, and Rodriguez. For arbitrary groups, we also prove a new bound on the minimum degree $d$ such that the polynomials of degree $\leq d$ span the field of rational functions as a vector space over the invariant field. This latter quantity also bounds the degree $d$ such that the polynomials of degree $\leq d$ contain a copy of the regular representation of $G$, advancing an inquiry of Kollár and Tiep. The methods involve Euclidean lattices and Minkowski's geometry of numbers.
format Preprint
id arxiv_https___arxiv_org_abs_2604_18876
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Geometry of numbers and degree bounds for rational invariants
Blum-Smith, Ben
Crane, Sylvan
Guzman, Karla
Menenses, Alexis
Song-Hurewitz, Maxine
Commutative Algebra
We investigate degree bounds for fields of rational invariants of representations of finite groups. We prove many cases of a bound for $\mathbb{Z}/p\mathbb{Z}$ conjectured by Blum-Smith, Garcia, Hidalgo, and Rodriguez. For arbitrary groups, we also prove a new bound on the minimum degree $d$ such that the polynomials of degree $\leq d$ span the field of rational functions as a vector space over the invariant field. This latter quantity also bounds the degree $d$ such that the polynomials of degree $\leq d$ contain a copy of the regular representation of $G$, advancing an inquiry of Kollár and Tiep. The methods involve Euclidean lattices and Minkowski's geometry of numbers.
title Geometry of numbers and degree bounds for rational invariants
topic Commutative Algebra
url https://arxiv.org/abs/2604.18876